Multiple cavity mold



Feb. 13, 1951 J. R. HoBsoN 2,541,249

MULTIPLE cAvITY MOLD Filed Aug. 12, 1947 2 Sheets-Sheet l V1/[Q gig# ffy/045g. 2 Q

INVENTOR. JOHN R. HOBSON ATTORNEYS Feb. 13, 1951 J. R. HoBsoN MULTIPLE cAvITY MOLD 2 Sheets-Sheet 2 Filed Aug. l2, 1947 INVENTOR.l 1 JOHN R. HoBsoN ATTORNEYS Patented Feb. 13, 95

MULTIPLE CAVITY 4lVIOLD .lohn R. Hobson, West Hartford, Conn., assignor to Plax Corporation, Hartford, Conn., a corporation of Delaware Application August 12, 1947, Serial No. 768,163

This invention relates to the production of hollow articles, such as containers, from plastic materials which are capable of being softened and made workable by heating at relatively low temperatures and which may be expanded under fluid pressure into articles of desired shapes, and thereafter, rigidified. More particularly, the present invention relates to a novel multiple mold mechanism by means of which a plurality of articles may be simultaneously formed in the manner indicated.

It'has previously been proposed (see U. S. patents to Kopitke No. 2,260,750, issued October 28, 1946, and No. 2,349,176, issued May 16, 1944) t make hollow articles, such as, for example, containers and ornamental Christmas tree balls, from organic plastic materials by rst forming the material into a tubular form, closing the leading end of the tubular body of material, extruding the tubular body from connement as a closed-ended hollow body and blowing the closed tubular body into a single article within a mold and then to sever the blown or expanded article from the remaining tubular material. fication of this procedure involves pinching the leading end of the tubular material between the mold sections to form a closure either as an alternative or in addition to the aforementioned preclosing of the leading end.

The present invention provides improvements over molding methods and apparatus heretofore used to make hollow articles and has for its general object more economical production of such articles.

A further object of the invention is to provide a mold structure having a plurality of molding cavities in which to form a plurality of articles in a single molding operation.

A further object is to provide mechanism for closing the tubular material at a series of spaced points; and to so affect the closing of the material as to seal uid pressure within each of a series of articles during a single molding operation. The manner in which the above and other objects and advantages are accomplished or obtained will be pointed out or made apparent from the detailed description which follows and which has reference to the accompanying drawings which show two forms of molding apparatus embodying the invention. e

'In-'the drawings:

Fig. 1 is a vertical section of a double cavity mold in open position and showing a tube of plastic material all in accordance with one embodiment of the present invention;

A modi- Claims. (Cl. 1S-5) i iol 1liA

Fig.2 is a'v'iew similar to Fig. l showing the mold membersin their closed or molding position; 'f

Fig. 3 is a view similar to Fig. 2 showing the" plastic tubing blown to form two ornamental spheresor balls within the mold cavities;

Fig. 4 is a front elevation of the parting face of one of themold sections shown in Figs. l to 3;

Fig. 5 is a vertical section of a second multiple cavity mold in open position and showing a tube of plasticmaterial therein preparatory to being formed into three plastic containers;

Fig. 6' is a cross-sectional view taken on line --S of Fig. 5;

Fig. 7 `is va view similar to Fig. 5 showing the molding members in closed position; and y Fig. 8 is a view similar to Fig. '7 showing a sub sequent step in the forming of the containers. Referring more particularly to Figs. 1 to 4, inclusive, there is illustrated the outlet or extrusion' end l ofv a nozzle from which thermoplastic material is extruded in a tubular form 2.' For' details of a suitable extruder and extruder nozzle of which the outlet end I is a part, reference may be had to the aforementioned patentsto Kopitke. The closing of the leading end 2a of the tubular'material is aiected by the smearing action of a cut-oi knife blade 3 following comi' pletion of the preceding forming action. There" after the tubular material is extruded from the nozzle las an elongated bubble from which a plurality of molded articles areforined by the molding mechanism indicated generally by the numeral 4 in Figs. 1 to 4 of the drawings.

Referring more particularly to the details o the molding mechanism 4, it includes a pair of mold cavity members 5 and 6 which meet in a vertical plane and which are adapted to be moved between thetwopositions illustrated in Figs. 1 and 2. In the embodiment illustrated the interior of the molds are shaped to form Christmasv tree ballsvA and B and to that end have upper and lower spherical cavities 5a, 6a and 5b, 6b,-

respectively, and are provided with a pair of eye-2 let forming mechanisms intermediate the two spherical cavities. nism comprises a pair of opposing plungers 'l and 8 which are slidably mounted respectivelyin the mold-halves 5 and 6. The plungers l and 8 are respectively held retracted under compression by 1 springs la and 8a. which yforce the.

plungers outwardly to their normal or open' positions. that when pressed toward each other they close the tubular connection 2bY (Fig. 2) between the Each eyelet forming mecha-'1 The ends of the plungers are so shaped.

recesses in the plungers 8 following an eyeletr.)

forming operation.

The upper or following end of the tube 2" adjacent the blowhead I initially extends throughanVVV upper opening in the closed mold in tubular forni Q so as to permit the introductionhof VairA under pressure to blow the tubing 2( into contact with the mold cavities. f f

In addition to the eyelet or ring formingpinchjoi members 'i and 8 the mold mechanism 4 is providedA :withcooperating pinchfoft members Ssland lair i' chare.resndiiyelymumed" anzeiger rciprocai movement' on the' upper ends'of'ime: mqldlniembers 5. and 6., The l*pinch-offmembers normahy areheldbysprngsSa La" d' IIlz iri their retracted or open positions. in Figs, the pincilfofr members' s yaint were mty# a5l'-" tq a contactingfor closed position for cuttingl oiil superfluous` plastic material.' from. the,y upper' ball, and sealing the upper `ball underpressure.,

TheV mechanism for moving thepifnch-oi inem-V bers ,`8, 9 'and l() to theclosed or 'cut-olii posi-7 tions illustrated in Fig. 3 may take a variety -`oi' forms; the Ydetails of which are'notrls'hownirthe drawiljig,k but which may be: similart"theoper' ating"` mechanism and described 'in the aforeme tipned Patent 2,249,176 toxopitke, including tf a'{c 'tu'ating'` ends I2 ofadjustablejcntactsdrews: si mV 'no-those' indicated-at 226@ anqcziidjofthe" Kpitke patent; similarithe-mold'ppeiiirig clos ng" Ine'cha'nisriil fort actuating L the: mold tignes-and t is not iiiustratedyth mecnan s uiustrated in the .'aforsaidzjptent 9j Kapu b g illustrative o orieltype wliA emp .ym .4 A

"Theperation of the mechanismjhus farms-. cigsdina'y be's'ummaizea fouoii Agtuzur all formable Yeoriditifonun w ble withiathe open "mold'linemb'es `5a A Gsmeasy .wat the esegesi i211 sans@ sans@ pent of inspireren@ can h'r upon the Vmoldmember"5fan E "'mov theLlanes@nd` of bestimme? jumele-between tffefmold. Sections 4 and .anreviouselsineief the@ tne'ebpie into Contact withchermeidgcayiti h siedi and'orm, the eyelets or rings im; angmlb pri;L each bali.; Likewise the pinch-.oizmemliers Sami.

lfareactuated t0, Seal the uppefensiioi-the:11ppeif, ,ba;lliinderpressure.:V Preferably'. the plungv 'mold cavity members I3 and ist. Thereuponmas ersx; 1 and Y8 `*are actuatedv slightly.; yahead orig-they,

pinch-.01T members Sand I0..

While the above-described mold:A assexrilltly.I istv adapted to simultaneously produce,;.from asin: 5 @Walls gle extruded plastic bubble two blown hollow articles sealed under pressure, it will be appreciated that in forming Christmas tree ornaments, in accordance with the present invention, the extruded bubble might be formed into any desired additional number of like articles. Similarly, it will be apparent without additional drawings, that the positionl of the upper pairpf plungers l aiidj could be interchanged with fthezpinchoff members 9 and IU. An advantage of the illustrated molding apparatus over such a modification` lieshin the fact that the thickness, temperature and other physical factors of the centralportion of .the bubble 2 are practically the saine so' that the eyelets or rings of each ball willbe substantially the same in each of the nal as iiiustratedjinrigs. '5 ptn'mugihi's.' 1n it A todi 't'o'ftheg invention there illustrate rii rmemb'ers l3garid. lilih thei'rticlos tionsyarefprovided AWith single 'molina coils.trustedy 'andI Shaped to, form als'"eric-ifs; of, 4 threeI plastic bottles"C,D and EL".respectively", 'g externallythreaded necks 15e?. I5'Zari`d"i'.,. M

orriang '16 andl'i'whiclifare posedfa d"inftheclosed .psitionoffxtlli mo ab es, 'deseabasons-egim boe pinched-oilandfcon F cation. exists: 'through a channel.. `2B n theefissleala amifQr.. clssingfthe leading.. -.endV1 otihe'etlibinar;

' Within-the nezzlebyzaeiropriaie.Sme@

Ejsffsu stan illustratedgin--Fs ,7' thetmplimembers areIQSed abooutthe bubbleA and iiuid nlzessilre inirdiiceci; t. blew thebubble. ntaoiltact .theniold Qawtyz.' While., pressure is. lstiumantained, within-f theblown plastic, vthe pinch-01T members 2| and 22 are actuated to closevthe communicating opening 20 between the bottoms of .bottles D and E. Thereafter,.the cut-oir" shear blade 24 acts to' sever the plastic from the extrusion nozzle I9 and, at the same time, to smear the leading end of the plastic tubular material within the nozzle I9 preparatory to repeating the described cycle. By maintaining the two lower or connected containers C and D under pressure during the pinchoff operation, the described embodiment of the invention eliminates the possibility of either of the containers being collapsed by the action of the pinch-off members 2l and 22. even though the containers are not quite sufciently rigidified before they are removed from the mold., Upon cooling ofthe connected containers, the two lower bottles vC and D may be severed by means of suitable cutting mechanism (not shown) While the embodiment described in connection with Figs. 5 to 3 illustrates the formation of only three containers in a single forming operation, it will be appreciated that in accordance with the invention a larger number could be produced. In

the case of the formation of an even number of bottles, it is preferable to form them in connected pairs under pressure in the -manner of C and D.

Various changes may be made in the details ofconstruction and in the performance of the if.

method without departing from the scope of the claims. rEhe invention may be employed in forming tubing orhollow articles or containers from thermosetting as well as thermopastic compositions, it being understood that where thermosetting compositions are employed, the articles will be hardened or rigidi-led by further heating rather than by cooling.

Having thus described my invention, what I claim is:

1. The process of forming hollow articles of organic plastic material which comprises extruding a vertically suspended tube of such material from an extrusion nozzle, closing a sectional mold about the suspended tube, closing the leading end of said tube, admitting a gaseous pressure medium into said tube through a blowhead in said extrusion nozzle and expanding the closed tube t the shape of said mold, and sealing said tube at spaced points to form a plurality of spaced, sealed sections of said tubular material.

2. The process oi forming hollow articles of organic plastic material which comprises extruding a vertically suspended tube of such material from an extrusion nozzle, closing a sectional mold z about the suspended tube, closing the leading end of said tube between the mold sections, admitting a gaseous pressure medium into said closed tube through a blowhead in said extrusion nozzle and expanding said closed tube to the shape of said mold, sealing said tube at spaced points to form a plurality of spaced, sealed sections of said tubular material, and separating the Sealed sections within the mold.

3. The process of forming hollow articles of organic plastic material which comprises extruding a vertically suspended tube of such material having a closed leading end from an extrusion nozzle, closing a sectional mold about the suspended tube, admitting gaseous medium under -pressure into said closed tube through a blowhead in said extrusion nozzle and expanding said closed tube to the shape of said mold, sealing said tube at spaced points while maintaining the gaseous medium under pressure and trapping said 6 medium under pressure within spaced sections of said tubular material, and rigidifying and separating said spaced sections.

4. The process of forming hollowcontainers of organic plastic material which comprises extruding a vertically suspended tube of such material from an extrusion nozzle into a blow mold having a plurality of cavities, closing the leading end of said tube, admitting a gaseous medium under pressureinto said tube through a blowing a tube of such material from an extrusionv nozzle, closing the leading end of said tube, ex-A panding said closed tube with internal air pres sure into a plurality of shaped articles in arnold having a plurality of article forming cavities, closing said tube at spaced points while maintaining the application of said pressure medium and trapping said medium under pressure within said spaced articles.

6. The process oi forming hollow articles of' organic plastic material which comprises closing a sectional mold about a tube of such material having a closed end, admitting gaseous pressure medium into said tube through a blowhead and expanding said closed tube to the shape of said mold, sealing said tube at spaced points while maintaining the application of said pressure medium and trapping said medium under pressure within spaced sections of said tubular material.

'7. Apparatus for forming hollow articles from organic plastic material comprising a mu1tisec tion mold movable between opened and closed positions and having a plurality of connected mold cavities wherein a bubble of plastic material is expanded by a fluid pressure medium into a plurality of hollow articles, and means for closing said expanded bubble at spaced points and sealing the pressure medium in each of the plurality of hollow articles.

8. Apparatus for forming hollow articles from organic plastic material comprising a multi-section mold movable between opened and closed positions and having a plurality of connected mold cavities wherein a bubble of plastic material is expanded by a fluid pressure medium into a plurality of hollow articles, and means including a device for forming an eyelet on each of said articles for closing said expanded bubble at spaced points and sealing the pressure medium in each of the plurality of hollow articles.

9. Apparatus for forming hollow articles from organic plastic material comprising a multi-section mold movable between opened and closed positions and having a plurality of large mold cavities and a restricted connecting cavity wherein a tubing of plastic material is expanded by a fluid pressure medium into a series of connected hollow articles, and operable means for closing the portion of the tubing in the restricted connecting cavity, and operable means for closing the tubing and severing the hollow articles from the unexpanded tubing.

10. Apparatus for forming hollow articles from organic plastic material comprising a multi-section mold movable between opened and closed rmsitfcsfra .havinga elomgfate`c-'u'imldffcmaisl ineluding--enlarged'Lportonslseparatedfby a rel stricted portion Whereifmasingle tube 4of' fpla-stic material 'isexpanded by v a iii-iid pressure medium,

and: means-forseveringand closing theexpanded'l tube'lntermeiate expanded portions;-

llb The-process of forming holloW--art-icles-of plastic material whichff'eomprises forminga tube ctliel material., closing' ai sectional mold about the-tube, admittinga fluidi-pressure medium into theitube andblows/fing the tuloeinto a plurality of' connected.YA blown# articles: Within the -mold, clos'- ing'the blown tube atpoints spaeedfat least twicethe lengthrfof one of the articles, and severingthe blow-n tubing' intermediate the closed 'points -nto` agr-plurality of separate vhollow articles each closedl at1 fatz l'l'eastonev end;

12:Theaprocess of forming A'hol-low articles-or thermoplaste material whichL comprises forming oflthemateriala-tube at leasttwicetlie length of meot-the completed articles, closing asection-al'l mold =aboutthe tube, elosing-oneend of' ther tuioe, admitting a--vflud pressure-mediumfntfthe tubethrmrgh the otherr` endy and. blowing 'thetub'eV Within said v'molds into a plurality of eonnectetblown-articles, closing'said tube at pointy ati` leastftW-ice the length of one'of the articles 'from sa'dfclosed. endl, and'- severing the-blown-tubing1 intermediate the closed points into aplurali-ty o5' separate-rhollowfarticles:each closed at at least oneend,

13;" The Mprocess of for-ming hollow articlesfofIV thermoplastic material which comprises forming a-ftubeeffthe material, Vclosing a sectional mold e aboutie-#metete amusing'- Asrfifv l fi-um mw me fmt-ef amfbrowingm tete-mmapluralityoconnectec blownr articles; and *closing saidtubeat afoint irlterme'di'ate adjacent. Vblown' Y articles? 14. The-process -zicitedA inA claim 1'3`- andi irrcludi imgl sevear'ngfv the Yblowrr tubinginto' awpluralty of? hollow fartileseaclr cls'ediat atleast 'one iend.

15:' The-process of' frminghollow'articles of" therxnoplastrcc materi-ali'ihiclii comprises forming a'tube o ftlieamaterial; closing;ja.'^'se tior1alimold about* the tube,-A ad-mitting'a tiicl*pressure"me-2- dimmi-into the tube vand 4blcmvingY the- Vtikrerlto plurality ofconneeted blown articles; andfizlosi gi f andfsever-igtheffblown-tubing into vv*plurality"ofi REFEaENoEsfcITED The; following .ref 'rences are off recordfi .thel`r 

